Wormlike Micellar Aggregates of Saponins from Ilex paraguariensis A. St. Hil. (mate): A Characterisation by Cryo-TEM, Rheology, Light Scattering and Small-Angle Neutron Scattering

Biomedical Effects of the Phytonutrients Turmeric, Garlic, Cinnamon, Graviola, and Oregano: A Comprehensive Review

Phytonutrients are plant foods that contain many natural bioactive compounds, called phytochemicals, which show specific biological activities. These phytonutrients and their phytochemicals may play an important role in health care maintaining normal organism functions (as preventives) and fighting against diseases (as therapeutics). Phytonutrients’ components are the primary metabolites (i.e., proteins, carbohydrates, and lipids) and phytochemicals or secondary metabolites (i.e., phenolics, alkaloids, organosulfides, and terpenes). For years, several phytonutrients and their phytochemicals have demonstrated specific pharmacological and therapeutic effects in human health such as anticancer, antioxidant, antiviral, anti-inflammatory, antibacterial, antifungal, and immune response. This review summarizes the effects of the most studied or the most popular phytonutrients (i.e., turmeric, garlic, cinnamon, graviola, and oregano) and any reported contraindications. This article also presents the calculated physicochemical properties of the main phytochemicals in the selected phytonutrients using Lipinski’s, Veber’s, and Ghose’s rules. Based on our revisions for this article, all these phytonutrients have consistently shown great potential as preventives and therapeutics on many diseases in vitro, in vivo, and clinical studies.

Interfacial and emulsifying properties of purified glycyrrhizin and non-purified glycyrrhizin-rich extracts from liquorice root (Glycyrrhiza glabra)

This study compared the interfacial and emulsifying properties of purified saponins and non-purified saponin-rich extracts of Glycyrrhiza glabra, and highlighted potential mechanisms by which crude surface-active compositions, such as liquorice root extract (LRE), act as emulsifiers. LRE presented different fluid properties, in comparison to purified glycyrrhizin (PG), at equivalent glycyrrhizin concentrations. Particularly, it exhibited limited glycyrrhizin fibrilization at pH < pKa and efficiently reduced the interfacial tension at the soybean oil/water interface, independently of pH. LRE also presented better emulsification properties, in comparison to PG samples. Emulsions prepared using LRE had lower droplet sizes when using higher oil mass fractions or lower homogenization pressures, which was attributed to 2 main factors: (i) efficient adsorption of glycyrrhizin molecules at relatively low interfacial curvatures, thus accelerating oil phase breakup during homogenization and (ii) sufficient coverage of newly generated droplets due to adsorption of residual surface-active components (e.g. proteins), thus minimizing droplet coalescence.

Mixing Natural and Synthetic Surfactants: Co-Adsorption of Triterpenoid Saponins and Sodium Dodecyl Sulfate at the Air-Water Interface

Saponins are highly surface active glycosides, derived from a wide range of plant species. Their ability to produce stable foams and emulsions has stimulated their applications in beverages, foods, and cosmetics. To explore a wider range of potential applications, their surface mixing properties with conventional surfactants have been investigated. The competitive adsorption of the triterpenoid saponin escin with an anionic surfactant sodium dodecyl sulfate, SDS, at the air-water interface has been studied by neutron reflectivity, NR, and surface tension. The NR measurements, at concentrations above the mixed critical micelle concentration, demonstrate the impact of the relative surface activities of the two components. The surface mixing is highly nonideal and can be described quantitatively by the pseudophase approximation with the inclusion of the quadratic and cubic terms in the excess free energy of mixing. Hence, the surface mixing is highly asymmetrical and reflects both the electrostatic and steric contributions to the intermolecular interactions. The relative importance of the steric contribution is reinforced by the observation that the micelle mixing is even more nonideal than the surface mixing. The mixing properties result in the surface adsorption being largely dominated by the SDS over the composition and concentration range explored. The results and their interpretation provide an important insight into the wider potential for mixing saponins with more conventional surfactants.

Self-Assembly of the Bio-Surfactant Aescin in Solution: A Small-Angle X-ray Scattering and Fluorescence Study

This work investigates the temperature-dependent micelle formation as well as the micellar structure of the saponin aescin. The critical micelle concentration ( c m c ) of aescin is determined from the concentration-dependent autofluorescence (AF) of aescin. Values between c m c aescin , AF (10 ∘ C) = 0.38 ± 0.09 mM and c m c aescin , AF (50 ∘ C) = 0.32 ± 0.13 mM were obtained. The significance of this method is verified by tensiometry measurements. The value determined from this method is within the experimental error identical with values obtained from autofluorescence ( c m c aescin , T ( WP ) (23 ∘ C) = 0.33 ± 0.02 mM). The structure of the aescin micelles was investigated by small-angle X-ray scattering (SAXS) at 10 and 40 ∘ C. At low temperature, the aescin micelles are rod-like, whereas at high temperature the structure is ellipsoidal. The radii of gyration were determined to ≈31 Å (rods) and ≈21 Å (ellipsoid). The rod-like shape of the aescin micelles at low temperature was confirmed by transmission electron microscopy (TEM). All investigations were performed at a constant pH of 7.4, because the acidic aescin has the ability to lower the pH value in aqueous solution.

Saponins - Self-assembly and behavior at aqueous interfaces

Saponins are interfacially active ingredients in plants consisting of a hydrophobic aglycone structure with hydrophilic sugar residues. Variations in aglycone structure as well as type and amount of sugar residues occur depending on the botanical origin. Saponins are a heterogeneous and broad class of natural substances and therefore the relationship between molecular structure and interfacial properties is complex and, yet, not completely understood. A wide range of research focused either on structural elucidation of saponins or interfacial properties. This review combines recent knowledge on structural features with interfacial properties and draws conclusions on how saponin structure affects interfacial properties. Fundamental understanding on interfacial configuration of individual saponin molecules at the interface distinctly increased. It was shown that interfacial configuration may differ depending on botanical origin and thus structure of the saponins. The formation of strong viscoelastic interfacial films by some saponins was attributed to hydrogen bonds between neighboring sugar residues. Few studies analyzed the relationship between botanical origin and interfacial rheology and derived main conclusions on important structural features. Saponins with a triterpenoid structure are most likely to form viscoelastic films, which result in stable foams and emulsions. The aglycone subtype may also affect interfacial properties as triterpenoid saponins of oleanane type formed most stable interfacial networks. But for more reliable conclusions more saponins from other aglycone subtypes (dammarane, ursolic) have to be analyzed. To-date only extracts from Quillaja saponaria Molina are approved for food products and many studies focused on these extracts. From experiments on interfacial rheology a reasonable model for supramolecular structure of Quillaja saponins was developed. It was further shown that Quillaja saponins may form micelles loaded with hydrophobic substances, nano-emulsions and stable foams. In combination proteins an increase in interfacial film stability may be observed but also negative phenomena like aggregation of oil droplets in emulsions may occur.

Dissipative particle dynamics study on self-assembled platycodin structures: the potential biocarriers for drug delivery

Platycodin, as a kind of plant based biosurfactants, are saponins which derived from the root of Platycodon grandiflorum A. DC. It has been confirmed that platycodin have the potential to enhance the solubility of hydrophobic drugs and function as the drug carrier, which depends on their micellization over critical micelle concentration (CMC) in aqueous solutions. With the purpose of investigating the effects of influencing factors on the micellization behavior of platycodin and obtaining the phase behavior details at a mesoscopic level, dissipative particle dynamics (DPD) simulations method has been adopted in this study. The simulations reveal that a rich variety of aggregates morphologies will appear with changes of structure or the concentration of saponins, including spherical, ellipse and oblate micelles and vesicles, multilamellar vesicles (MLVs), multicompartment vesicles (MCMs), tubular and necklace-like micelle. They can be formed spontaneously from a randomly generated initial state and the result has been represented in the phase diagrams. Furthermore, deeper explorations have been done on the concentration-dependent structure variation of spherical vesicles as well as the formation mechanism of MLVs. This work provides insight into the solubilization system formed by platycodin, and may serve as guidance for further development and application in pharmaceutical field of platycodin and other saponins.

Effect of flavonoids and saponins extracted from black bean (Phaseolus vulgaris L.) seed coats as cholesterol micelle disruptors

Strategies for reducing plasma cholesterol have been focused on reducing the absorption or synthesis of cholesterol. The aim of this study was to correlate the content of flavonoids and saponins in black bean (Phaseolus vulgaris L.) seed coats extracts with a potential effect in lowering cholesterol absorption by the inhibition of cholesterol micellar solubility. Extracts with different flavonoids and saponins concentration were obtained from a Box-Behnken design used to optimize extraction temperature, stirring time and solvent composition. Major flavonoids and saponins were quantified by HPLC-PDA-ELSD and confirmed through mass spectrometry. Contrary to the flavonoid content, saponins were correlated to the inhibitory effect of cholesterol micelle solubility as an approach to a potential reduction of cholesterol absorption. Extracts with the highest saponin content strongly inhibited cholesterol micellization with values of 55.4 ± 1.9 %, while stigmasterol used as control, only reached 12 ± 2.3 % at the same concentration (5 mg/ml). The optimal extracting conditions for saponins were 25 °C, during 3 h in 85 % aqueous-methanol. Correlations of inhibitory effect of cholesterol micellar solubility with the content of each identified saponin suggested that the reduction of cholesterol micellization depends on the C-22 substitution of saponins.

The activity of mate saponins (Ilex paraguariensis) in intra-abdominal and epididymal fat, and glucose oxidation in male Wistar rats

ETHNOPHARMACOLOGICAL RELEVANCE

Ilex paraguariensis A. St. Hilaire (mate) has traditionally been used in several South American countries to prepare tea-like beverages having stimulant effects on the CNS and appetite. In recent years, however, mate preparations have been recommended putatively as an appetite suppressant and slimming remedy. Moreover, studies carried out on either normal or diet-induced obese rats treated with mate extracts revealed anti-obesity and satiety effects, thus refuting ethnopharmacological data. In this work, the effect of mate on the intra-abdominal and epididymal fat, and glucose oxidation levels after oral administration in male Wistar rats, was studied using crude extract from leaves, unripe fruits, and a chemically well-defined purified saponin fraction (MSF).

MATERIAL AND METHODS

Saponin, polyphenol and methylxanthine contents in MSF were analyzed by HPLC-PDA and UPLC/Q-TOF-MS. Crude extracts from mate leaves (LAE) and unripe fruits (FHE) were assayed for comparison purposes. Male Wistar rats fed with standard diet and water ad libitum were used as the control group.

RESULTS

The fat weight and both liver and adipose glucose oxidation were reduced significantly by MSF (35, 90 and 60%, respectively), while LAE and FHE were less active. Also, a significant lowering of the blood triglycerides level was observed in rats treated with MSF and LAE. All creatinine, urea, and transaminase plasma levels remained unaffected no matter what mate preparation was considered. It is also worth pointing out that the glucose blood level was increased after treatment with FHE. This finding did not correlate either with the content of methylxanthines, polyphenols or saponins.

CONCLUSION

A reduction in both visceral fat weight and glucose oxidation of hepatic and adipose tissue in healthy rats fed with a standard diet could be ascribed to a purified mate saponin fraction from unripe fruits. These findings agree with former studies carried out with crude mate extracts and also suggest their potential use as an anti-obesity preparation. Nonetheless, further in vivo experiments are still required to corroborate its effect on human beings.

LC-UV assay method and UPLC/Q-TOF-MS characterisation of saponins from Ilex paraguariensis A. St. Hil. (mate) unripe fruits

INTRODUCTION

Ilex paraguariensis A. St. Hil. (mate) is known in several South American countries because of the use of its leaves in stimulant herbal beverages. High saponin contents were reported in mate leaves and unripe fruits that possess a dissimilar composition. Two LC-UV methods previously reported for mate saponins assay focused on mate leaves and the quantification of the less polar saponin fraction in mate fruits.

OBJECTIVE

To develop and validate a LC-UV method to assay the total content of saponins in unripe mate fruits and characterise the chemical structure of triterpenic saponins by UPLC/Q-TOF-MS.

METHODOLOGY

From unripe fruits of mate a crude ethanolic extract was prepared (EX40) and the mate saponin fraction (MSF) purified by solid phase extraction. The LC-UV method was validated using ilexoside II as external standard. UPLC/Q-TOF-MS was adjusted from the LC-UV method to obtain the fragmentation patterns of the main saponins present in unripe fruits.

RESULTS

Both LC-UV and UPLC/Q-TOF-MS methods indicate a wide range of Ilex saponins polarity. The ilexoside II and total saponin content of EX40 were 8.20% (w/w) and 47.60% (w/w), respectively. The total saponin content in unripe fruits was 7.28% (w/w). The saponins present in MSF characterised by UPLC/Q-TOF-MS are derived mainly from ursolic/oleanolic, acetyl ursolic or pomolic acid.

CONCLUSION

The validated LC-UV method was shown to be linear, precise, accurate and to cover several saponins previously isolated from Ilex species and could be applied for the quality control of unripe fruit saponins.